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biology ZAHRA NEW USE > topic 4 > Flashcards

topic 4 Flashcards

1
Q

dna in euk vs prok similarities

A

nucleotide structure is identical - deoxyribose attached to phosphate and base
adjacent nucleotides joked by phosphodeister bonds and comp bases by hydrogen bonds
dna in mitochondria and chloroplasts have a similar structure to dna in prok

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2
Q

differences in elk and prok dna

A

euk has longer linear dna prok is circular
euk associated with histone protiens
euk contains introns prok doesnt

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3
Q

chromosome

A

long linear dna associated with histones and in the nucleus of euk cells

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4
Q

gene

A

sequence of dna nucleotide bases that code for an amino acid sequence of a polypeptide
or functional RNA

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5
Q

locus

A

fixed position a gene occupies on a particular dna molecule

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6
Q

universal

A

the same base triplet code for the same amino acid in all organisms

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7
Q

non coding base sequences

A

dna that doesnt code for an amino acid
between genes
within genes are introns

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8
Q

genome

A

complete set of genes in a cell

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9
Q

tRNA vs mrna

A

both are single polynucleotide strands
tRNA is folded into clover leaf shape but mrna is linear
tuna has hydrogen bonds between base pairs mrna doesnt
tRNA is a short fixed length but mrna is long and variable
tRNA has an anticodon mrna has codons
trna has an amino acid binding site mrna doesnt

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10
Q

transcription

A

dna helices breaks hydrogen bonds between complementary base pairs
one dna strand acts as a template
free rna nucleotides align next to their comp base pairs on template strand
in rna U replaces T
rna polymerase joins adjacent rna nucleotides
forming phosphodiester bonds via condensation
pre mrna formed and spliced to remove introns

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11
Q

difference in the production of mrna in prok vs euk

A

pre mrna formed in euk whereas mrna produced directly in prok because genes in prok dont contain introns so no splicing

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12
Q

translation

A

mrna attaches to ribosome and ribosome moves to start codon
tRNA brings specific amino acid and trna anticodon binds to comp mrna codon
ribosome moves along to next codon and another tuna binds bringing two amino acids to be joined by condensation reaction forming a peptide bond
using energy form hydrolysis of atp
tRNA released after amino acid joined polypeptide
ribosome moves along mrna to form polypeptide till stop codon reached

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13
Q

role of ATP in translation

A

hydrolysis of atp to add and pi releases energy
so amino acids join to trna and peptide bonds form between amino acids

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14
Q

tRNA role in translation

A

attaches to and transports a specific amino acid in relation to its anticodon
tRNA anticodon comp to mrna codon forming hydrogen bonds
2 tuna bring amino acids together so peptide bond can form

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15
Q

ribosome role in translation

A

mrna binds to ribosome with space for two codons
allows tRNA with anticodon to bind
catalyses formation of peptide bond between amino acids
moves along mrna to next codon

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16
Q

gene mutation

A

change in base sequence of dna
arise spot during dna replication

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17
Q

mutagenic agent

A

factor that increases the rate of mutation

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18
Q

how do mutations lead to production of non functional protiens or enzymes

A

change in sequence of base triplets in dna
change sequence of codons on mrna
change position of bonds
changes tertiary structure
enzyme active site changes shape so substrate cant bind enzyme substrate complexes cant form

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19
Q

substitution

A

base in dna replaced by another base
changes on triplet so changes one mrna codon
one amino acid in polypeptide changes
tertiary structure may change if position of bonds change
or may not change AA bc degenerate or mutation in intron

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20
Q

deletion

A

one base removed from dna sequence
changes sequence of dna triplets from point of mutation
changes sequence of mrna codons after point of mutation
changes seq of AA in primary structure of polypeptide
changes position of bonds and tertiary structure

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21
Q

homologous chromsomes

A

same length same genes but maybe different alleles

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22
Q

diploid cell

A

2 complete sets of chromosome

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23
Q

haploid

A

single set unpaired chromosomes

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24
Q

meiosis

A

meiosis 1 separates homologous chromsomes so chromosomes arrange into homologous pairs
crossing over and independant segregation
meiosis 2 separates chromatids

25
Q

why is the chromosome number halved kin meiosis

A

homologous chromosomes are separated during meiosis 1

26
Q

crossing over

A

Homologous pairs of chromosomes form a bivalent
chiasmata form
alleles exchanged between chromsomes
creating new combos of maternal and paternal alleles on chromosomes

27
Q

indepedant segregation

A

Homologous pairs randomly align at equator so random which chromosome form each pair goes to each daughter cell
cresting Dif combos of eternal and paternal chromosomes

28
Q

difference in outcomes of meiosis and mitosis

A

mitosis 2 genetically identical daughter cells and meiosis four genetically different daughter cells
1 division In mitosis but 2 in meiosis
mitosis maintains the chromosome number whereas meiosis half the chromosome number as hc separate in meiosis
mitosis genetically identical meiosis genetically different

29
Q

meiosis importance

A

two divisions create haploid gametes
so diploid number is restored at fertilisation so chromosome number maintained between generations
independent segregation and crossing over creates genetic variation

30
Q

how do mutations in the number of chromsomes arise

A

spontaneously by chromosome non disjunction during meiosis
HC or sister chromatids fail to separate during meiosis
so some gametes have an extra or no chromosome

31
Q

genetic diversity

A

no of Dif alleles of genes in a population

32
Q

what are alleles and how do they arise

A

variation of a particular gene same locus different dna base sequence
arise by mutation

33
Q

population

A

group of interbreeding individuals of the same species

34
Q

Importance of genetic diversity

A

enables natural selection to occur
as in certain environments new allele of gene may benefit posessor
by resulting in change in polypeptide coded for that positively changes its properties
by giving poser a selective advantage and increases its chance of survival and reproductive success

35
Q

evolution

A

change in allele frequency over many generations in a population
occurring via natural selection

36
Q

principles of martial selection in the evolution of populations

A

random gene mutation result in new allele of gene
in certain environments the new allele may benefit the possessor giving them a selective advantage
possessors are more likely to survive and reproduce
advantageous alleles inherited by members of next generation
over many generations Allee increases in frequency in population

37
Q

anatomical

A

structural and physical features increasing chance of survival

38
Q

physiological

A

processes chemical reactions that increase an organism chance of survival

39
Q

Behavioural

A

ways in which an organism acts that increases its chance of survival

40
Q

directional selection

A

selective advantage to organism with extreme variation of trait so increase in organism with extreme trait

41
Q

stabilising selection

A

organisms with average trait have selective advantage so increase in frequency of organisms with average trait

42
Q

species

A

group of organisms that can interbreed to produce fertile offspring

43
Q

why are two different species unable to produce fertile offspring

A

different species have different chromosome numbers so offspring may have an odd chromosome number
so homologous pairs cant form and meiosis cant occur too produce gametes

44
Q

courtship behaviour

A

allows recognition of opposite sex
recognition of same species so fertile offspring produced
synchronises mating
indicates sexual maturity
establishes pair bond

45
Q

phylogenetic classification system

A

species arranged to groups called taxa based on evolutionary relationships
using hierarchy smaller groups are placed within larger groups and no overlap between groups

46
Q

advantage of binomial naming

A

universal
no confusion as many organisms have more than 1 common name

47
Q

two advances that have helped clarify evolutionary relationships between organisms

A

advances in genome sequencing allows comparison of dna base sequences
more difference in dna base sequence means more distantly related as mutations have built up over time

advances in immunology allowing comparison of protein tertiary structure higher amount of protein from ones species binds to antibody against the same protein from another species so more closely related as indicates similar amino acid sequence and tertiary structure

48
Q

biodiversity

A

variety of living organisms
can relate to habitats from small to local habitat

49
Q

community

A

all populations of different species that live in an area

50
Q

species richness

A

a measure of the number of different species in a community

51
Q

what does index of diversity do

A

describes the relationship between the number of different species in a community and the number of individuals in each species

52
Q

why is the index of diversity better than species richness

A

also takes into account the number of individual species
so takes into account that some species may be present in high or small numbers

53
Q

index of diversity formula

A

D = N(N-1) divided by n(n-1)
N being the total number of all species
n being the total number of organisms of each species

54
Q

farming techniques that reduce biodiversity

A

removal of woodland and hedgerows and monoculture, herbicides to kill weeds all reduce the variety of plants so fewer habitats and niches and less variety of food sources

pesticides to kill pests - predator population. of pests decreases

55
Q

balance between conservation and farming

A

conservation is required to increase biodiversity
but when implemented on farms yield can be reduced reducing profit

56
Q

how can biodiversity be increased in areas of agriculture

A

reintroduce field margins and hedgerows
reduce the use of pesticides
growing different crops in the same area
using Crop rotation of nitrogen fixing crops instead of fertilisers

57
Q

how can genetic diversity within or between species be measured

A

comparing frequency of measurable and observable characteristics
comparing the base sequence e of mrna and dna
comparing the amino acid sequence of a specific protein encoded by dna and mrna

58
Q

explain changes in methods of investigating genetic diversity overtime

A

early estimates made by inferring dna differences from measurable and observable characteristics
many coded for by more than one gene so difficult to distinguish and many influenced by environment not genes
gene technologies allowed this to be replaced why direct investigation of dna sequences

biology ZAHRA NEW USE (41 decks)

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